100) A 60-year-old man presents to his primary care physician for routine medical care. He has no complaints, takes no medications, and has a family history of DM. Examination is unremarkable. A screening laboratory test reveals a fasting blood glucose level of 152 mg/dL. One week later the test is repeated and a value of 144 mg/dL is obtained. Which of the following is the most likely cause of these findings?